#include "git-compat-util.h"
#include "hash.h"
#include "oidmap.h"

/**
 * Compare two oidmap entries for inequality.
 *
 * This is a callback function used by the hashmap to compare keys.
 * It compares two oidmap entries by their object ID.
 */
static int oidmap_neq(const void *hashmap_cmp_fn_data UNUSED,
		      const struct hashmap_entry *e1,
		      const struct hashmap_entry *e2,
		      const void *keydata)
{
	const struct oidmap_entry *a, *b;

	a = container_of(e1, const struct oidmap_entry, internal_entry);
	b = container_of(e2, const struct oidmap_entry, internal_entry);

	if (keydata)
		return !oideq(&a->oid, (const struct object_id *) keydata);
	return !oideq(&a->oid, &b->oid);
}

/**
 * Initialize an oidmap.
 *
 * @param map the oidmap to initialize
 * @param initial_size initial number of buckets in the hashmap
 */
void oidmap_init(struct oidmap *map, size_t initial_size)
{
	hashmap_init(&map->map, oidmap_neq, NULL, initial_size);
}

/**
 * Free an oidmap's entries and the map itself.
 *
 * @param map the oidmap to free
 * @param free_entries whether to also free the oidmap entries
 */
void oidmap_free(struct oidmap *map, int free_entries)
{
	if (!map)
		return;

	/* TODO: make oidmap itself not depend on struct layouts */
	hashmap_clear_(&map->map, free_entries ? 0 : -1);
}

/**
 * Get an entry from the oidmap.
 *
 * @param map the oidmap
 * @param key the key of the entry to get
 * @return the entry, or NULL if no entry was found
 */
void *oidmap_get(const struct oidmap *map, const struct object_id *key)
{
	if (!map->map.cmpfn)
		return NULL;

	return hashmap_get_from_hash(&map->map, oidhash(key), key);
}

/**
 * Remove an entry from the oidmap.
 *
 * @param map the oidmap to remove from
 * @param key the key of the entry to remove
 * @return the removed entry, or NULL if no entry was found
 */
void *oidmap_remove(struct oidmap *map, const struct object_id *key)
{
	struct hashmap_entry entry;

	if (!map->map.cmpfn)
		oidmap_init(map, 0);

	hashmap_entry_init(&entry, oidhash(key));
	return hashmap_remove(&map->map, &entry, key);
}

/**
 * Put an entry into the oidmap.
 *
 * @param map the oidmap
 * @param entry the entry to put into the map
 * @return the entry put into the map, or NULL if the put failed
 */
void *oidmap_put(struct oidmap *map, void *entry)
{
	struct oidmap_entry *to_put = entry;

	if (!map->map.cmpfn)
		oidmap_init(map, 0);

	hashmap_entry_init(&to_put->internal_entry, oidhash(&to_put->oid));
	return hashmap_put(&map->map, &to_put->internal_entry);
}
